Usually, in preparation of ethylene, various methods such as ethane cracking, petroleum degradation, combustion, acetylene hydrogenation and alcohol dehydration have been used. FIG. 1 is a diagram illustrating a conventional process of preparing ethylene, and simply describing the process of preparing ethylene illustrated in FIG. 1, first, when a hydrocarbon compound having two carbon atoms isolated from a De C2 column 2 is transferred to an acetylene converter 4, acetylene (C2H2) of the hydrocarbon compound having two carbon atoms is converted into ethylene (C2H4) or ethane (C2H6). Subsequently, after ethylene and ethane are transferred to a first C2S column 6, a part of the ethylene is isolated first, remaining ethylene and ethane are transferred to a second C2S column 8, followed by isolating and discharging ethylene, and ethane is recycled back to the preceding process, resulting in the obtainment of pure ethylene.